It is common practice during highway construction or repair to use concrete barriers as temporary walls between adjacent traffic lanes or to separate traffic lanes from construction zones. Such lane barriers have traditionally taken the form of individual, steel-reinforced concrete modules arranged in an end to end fashion. Individual barrier modules were transported to the site by truck and placed into position using cranes or other lifting devices. Shifting such a barrier from one lane to another requires picking up, moving and replacing each individual module. That procedure disrupts traffic, is time consuming, labor intensive and expensive.
Systems have recently been developed that enable a lane barrier to be rapidly shifted, either laterally or longitudinally, along a roadway so as to change the traffic pattern at will. Those systems typically comprise a series of concrete barrier modules linked together end to end through pivoted fastenings. The barrier modules, in cross-section, are provided with a relatively massive base, an upwardly extending, wall-like midsection and a T-shaped top section. A mobile transport vehicle is used to move the lane barrier or to transfer it from one lane side to the other. The transport vehicle includes a conveyor having a series of rollers that engage each barrier module at the underside of its T-shaped top section to lift, support and transfer the module from one place to another.
One such prior art system for moving a lane barrier is described in a patent to Quittner, U.S. Pat. No. 5,088,874. That system includes a series of wheeled barrier module transporting units arranged to straddle a length of highway barriers, to lift the barriers, and to move the length as a train. Another patent to the same inventor, U.S. Pat. No. 4,500,225, discloses barrier modules of a particular configuration including a T-shaped upper end connected to form a highway barrier. The patent also describes a barrier transfer device adapted to shift the barrier from one lane to a next adjacent lane. That transfer device employs a conveyor having rollers which engage the underside of the T-shaped upper module end to lift the modules, move them laterally and deposit them in a new position.
Other patents illustrating the use of barrier modules having a T-shaped upper section and systems for moving lengths of such interconnected modules include two patents to Peek, U.S. Pat. Nos. 5,246,305 and 5,253,951 and a patent to Duckett, U.S. Pat. No. 4,806,044. All of those prior art systems use wheels or rollers that pick up the barrier modules by engaging the underside of the outwardly extended top module flange. While those systems generally work well, all require that the underside of the top flange or T-section of the modules be in good condition without large chips, breaks or gouges. Such imperfections interfere with the rollers and even stall operation of the transfer conveyor.
In the original placement of barrier modules to form a moveable highway barrier, it is common practice to transport the modules to a site by truck. A fork lift is then used to load and unload modules from the truck and to place the modules in position for interconnection to form a continuous barrier train. Individual barrier modules are typically about 1 meter in length and are ordinarily arranged for truck transport in groups of two set end to end and placed laterally across the truck bed. That arrangement allows ready access to a fork lift. The fork lift tines are set apart a distance just greater than the thickness of the middle wall or web of the modules so that the top surface of the tines engages the underside of the top module flange.
Handling the modules in this way frequently results in damage being inflicted to the critical underside of the top flange by the fork lift tines. Those damaged modules ordinarily cannot be repaired but must be discarded. In light of this background, it can readily be appreciated that a system that avoids damage to barrier modules during their loading and unloading offers considerable advantage and economy.